A system on chip, SoC, is an integrated circuit, wherein different kinds of components of an electronic system are integrated on a single chip. A system on chip can comprise microprocessor cores, memory blocks, timing sources such as oscillators, interface circuits and many other circuits and components, for instance voltage regulators or power management circuits. A chip or integrated circuit on which the system on chip is integrated comprises signal pins. These pins can comprise general purpose input output pins. A group of GPIO pins can form a GPIO port of the integrated circuit. GPIO pins of an integrated circuit have no special purpose defined and are unused by default. GPIO pins are mostly found in integrated circuits and devices with pin scarcity, for instance a system on chip, embedded and custom hardware or programmable logic devices. GPIO pins can be configured to be input or output pins. It is possible that a group of pins can be switched as a group to form either an input or an output. In other integrated circuits, each GPIO pin can be set up flexibly to accept or source different logic voltages with configurable signal driving strengths and configurable pull ups and pull downs.
In conventional integrated circuits having GPIO pins, the actual GPIO signals applied to the GPIO pins are not checked in a robust manner. Conventional systems rely on the user to create a self-checking scheme, possibly by use of a redundant signal line. With increased demands on safety systems and ever more elaborate techniques to protect data, there is currently no emphasis on the actual data being written to GPIO ports or read from GPIO ports of a system on chip.
Accordingly, there is a need for a method and apparatus for monitoring general purpose input output, GPIO, signals at GPIO pins to enhance safety in a safety-critical system or environment.